French far-right leader and presidential candidate Marine Le Pen addresses supporters during an election campaign rally in Nice on Thursday.

French far-right presidential candidate Marine Le Pen says she "abhors" Holocaust doubters amid a scandal involving a senior official in her party.

Le Pen has made the comment after allegations that a vice president of her National Front party expressed skepticism about Nazi gas chambers.

Le Pen has worked to clean up the image of her National Front party to make it an acceptable alternative, and noted in an interview on BFM-TV that in 2015 she forced her father out of the party he founded and led for 40 years after he repeated a statement diminishing the Holocaust, for which he had been convicted.

Le Pen said that today "there is no one in the direction of the National Front who defend these theses."

Rival candidate Emmanuel Macron has paid homage to Nazi victims, urging voters not to repeat "the darkest page" of modern French history by forgetting the horrors of World War II.

Macron walked slowly through the site of the deadliest massacre in Nazi-occupied France, the village of Oradour-sur-Glane in western France.

In 1944, an SS armored division herded villagers into barns and a church, blocked the doors, and set the village ablaze. A total of 642 people died, and only six survived. The town's ruins are preserved as a testimony to Nazi horrors.

Macron warned that "to forget ... is to take the risk of repeating history and these errors."

He is trying to distinguish himself from Le Pen, whose party's past is stained by anti-Semitism.